Rapid Load Testing on Piles: Interpretation Guidelines

A Rapid Load Test (RLT) developed to determine the initial stiffness and bearing capacity, is an economical and practical alternative for a Static Load Test (SLT) . However, the application of RLT used to be hampered by uncertainty about the interpretation of the test results. These guidelines attempt to offer clear guidance on the available analysis techniques and their reliability. These guidelines are related to an international standard which is drawn up by CEN and can be used in two ways: Straightforward interpretation of test results, chapter 1-3 Interpretation with additional background information about the possibilities and limitations, chapter 4-8 The chapters 1 and 2 deal with the execution of the test and the presentation of the results. Chapter 3 gives a general overview of existing interpretation methods. This chapter refers to step-by-step descriptions of the two advised interpretation methods. The aspects which are important for the interpretation are discussed in chapter 4. It turns out that the inertia of the pile should be taken into account. In clay soil the rate effect (the dependency of strength and stiffness on loading rate) must also be taken into account. In sand and silt the generation of pore water pressures during an RLT plays a role. The velocity of the RLT is such, that the reaction of sand and silt might be considered as partially drained. These guidelines indicate how these effect can be compensated to obtain the static resistance in the final results. Chapter 5 presents two interpretation methods (A method for piles in sand, gravel, silt and piles on rock and a method for piles in clay). For practical use, the methods are described in a step-by-step scheme in an Appendix of these guidelines.